An error message is created using 2 translated strings which is error prone for translators:

This is the code from current git:

              fatal (fstart, _("missing separator%s"),
                     (cmd_prefix == '\t' && !strneq (line, "        ", 8))
                     ? "" : _(" (did you mean TAB instead of 8 spaces?)"));
http://git.savannah.gnu.org/cgit/make.git/tree/read.c#n1123

In fact it is wrong in the Italian translation:
"separatore %s mancante".

A least this needs a "translators" comment telling that the %s must be at the end of the string.

A possible fix is using two different strings:
_("missing separator")
_("missing separator" (did you mean TAB instead of 8 spaces?))